Anode for secondary battery, secondary battery, and method of manufacturing anode for secondary battery

Abstract

An anode for secondary battery capable of improving cycle characteristics, a secondary battery using the anode, and a method of manufacturing an anode for secondary battery are provided. An anode active material layer is formed by vapor phase deposition method, and contains Si as an element. In the anode active material layer, there are a plurality of primary particles grown in the thickness direction. The primary particles aggregate and form a plurality of secondary particles. At least some of the primary particles have shape curved in the identical direction to an anode current collector on the cross section in the thickness direction. Thereby, stress due to expansion and shrinkage due to charge and discharge can be relaxed.

What is claimed is: 
     
       1. A secondary battery comprising:
 a cathode; 
 an anode; and 
 an electrolyte, 
 wherein,
 the anode comprises an anode current collector and an anode active material layer containing silicon (Si) as an element on the anode current collector, 
 the anode active material layer has a plurality of primary particles grown in one layer on the anode current collector and in contact with the anode current collector, 
 at least some of the plurality of primary particles are adjacent and joined to each other along a direction parallel to a surface of the anode current collector and aggregate to form a secondary particle, 
 said anode active material layer has a plurality of distinct secondary particles, 
 respective grooves are formed between adjacent secondary particles separating the adjacent secondary particles from each other, each groove being wider at an opening of the groove than at a bottom of the groove, the bottom of the groove comprising a surface of the anode active material layer, 
 each secondary particle comprises more than two primary particles that are joined and curved in an identical direction with respect to each other when viewed in cross section of the secondary battery along a thickness direction of the anode current collector, 
 the anode has a region including at least one groove and at least one set of adjacent secondary particles, and 
 the anode active material layer is in contact with an entire surface of the anode current collector throughout the entire region. 
 
 
     
     
       2. The secondary battery according to  claim 1 , wherein the primary particles having the curved shape are structured such that the primary particles are effective to inhibit a shape destruction of the anode active material layer and a peeling of the anode active layer from the anode current collector. 
     
     
       3. The secondary battery according to  claim 1 , wherein the anode current collector comprises a metal material alloyed with silicon. 
     
     
       4. The secondary battery according to  claim 1 , wherein the anode current collector comprises a plurality of layers, the plurality of layers including a first layer that contacts the anode active material layer, the first layer comprising a metal material alloyed with silicon. 
     
     
       5. The secondary battery according to  claim 1 , wherein the bottom of the groove is closer to a side of the anode active material layer that is adjacent to the anode current collector than to a side of the anode active material that is opposite to the anode current collector.